4 files changed, 40 insertions, 51 deletions

diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index f5cb3550e..942b5b945 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -190,10 +190,7 @@ impl AnalysisImpl {
             Some(it) => it,
         };
         let root = descr.crate_root();
-        let file_id = root
-            .source()
-            .as_file()
-            .expect("root module always has a file as a source");
+        let file_id = root.source().file_id();
 
         let crate_graph = self.db.crate_graph();
         let crate_id = crate_graph.crate_id_for_crate_root(file_id);
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index e7b6a81f4..0f84b2d61 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -131,6 +131,10 @@ impl SourceFileItems {
             .unwrap();
         id
     }
+    pub fn id_of_source_file(&self) -> SourceFileItemId {
+        let (id, _syntax) = self.arena.iter().next().unwrap();
+        id
+    }
 }
 
 impl Index<SourceFileItemId> for SourceFileItems {
diff --git a/crates/ra_hir/src/module/imp.rs b/crates/ra_hir/src/module/imp.rs
index 76ea129a7..0eec38797 100644
--- a/crates/ra_hir/src/module/imp.rs
+++ b/crates/ra_hir/src/module/imp.rs
@@ -66,7 +66,7 @@ fn create_module_tree<'a>(
 
     let source_root = db.source_root(source_root);
     for &file_id in source_root.files.iter() {
-        let source = ModuleSource::SourceFile(file_id);
+        let source = ModuleSource::new_file(db, file_id);
         if visited.contains(&source) {
             continue; // TODO: use explicit crate_roots here
         }
@@ -126,7 +126,7 @@ fn build_subtree(
                             visited,
                             roots,
                             Some(link),
-                            ModuleSource::SourceFile(file_id),
+                            ModuleSource::new_file(db, file_id),
                         ),
                     })
                     .collect::<Cancelable<Vec<_>>>()?;
@@ -157,13 +157,8 @@ fn resolve_submodule(
     name: &SmolStr,
     file_resolver: &FileResolverImp,
 ) -> (Vec<FileId>, Option<Problem>) {
-    let file_id = match source {
-        ModuleSource::SourceFile(it) => it,
-        ModuleSource::Module(..) => {
-            // TODO
-            return (Vec::new(), None);
-        }
-    };
+    // TODO: handle submodules of inline modules properly
+    let file_id = source.file_id();
     let mod_name = file_resolver.file_stem(file_id);
     let is_dir_owner = mod_name == "mod" || mod_name == "lib" || mod_name == "main";
 
diff --git a/crates/ra_hir/src/module/mod.rs b/crates/ra_hir/src/module/mod.rs
index 3ae83d8cb..fa9ee94eb 100644
--- a/crates/ra_hir/src/module/mod.rs
+++ b/crates/ra_hir/src/module/mod.rs
@@ -14,7 +14,7 @@ use ra_db::{SourceRootId, FileId, FilePosition, Cancelable};
 use relative_path::RelativePathBuf;
 
 use crate::{
-    DefLoc, DefId, Path, PathKind, HirDatabase, SourceItemId,
+    DefLoc, DefId, Path, PathKind, HirDatabase, SourceItemId, SourceFileItemId,
     arena::{Arena, Id},
 };
 
@@ -37,7 +37,8 @@ impl Module {
         db: &impl HirDatabase,
         file_id: FileId,
     ) -> Cancelable<Option<Module>> {
-        Module::guess_from_source(db, file_id, ModuleSource::SourceFile(file_id))
+        let module_source = ModuleSource::new_file(db, file_id);
+        Module::guess_from_source(db, module_source)
     }
 
     /// Lookup `Module` by position in the source code. Note that this
@@ -51,17 +52,16 @@ impl Module {
         let module_source = match find_node_at_offset::<ast::Module>(file.syntax(), position.offset)
         {
             Some(m) if !m.has_semi() => ModuleSource::new_inline(db, position.file_id, m),
-            _ => ModuleSource::SourceFile(position.file_id),
+            _ => ModuleSource::new_file(db, position.file_id),
         };
-        Module::guess_from_source(db, position.file_id, module_source)
+        Module::guess_from_source(db, module_source)
     }
 
     fn guess_from_source(
         db: &impl HirDatabase,
-        file_id: FileId,
         module_source: ModuleSource,
     ) -> Cancelable<Option<Module>> {
-        let source_root_id = db.file_source_root(file_id);
+        let source_root_id = db.file_source_root(module_source.file_id());
         let module_tree = db.module_tree(source_root_id)?;
 
         let res = match module_tree.any_module_for_source(module_source) {
@@ -209,10 +209,7 @@ impl ModuleTree {
 /// `ModuleSource` is the syntax tree element that produced this module:
 /// either a file, or an inlinde module.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub enum ModuleSource {
-    SourceFile(FileId),
-    Module(SourceItemId),
-}
+pub struct ModuleSource(SourceItemId);
 
 /// An owned syntax node for a module. Unlike `ModuleSource`,
 /// this holds onto the AST for the whole file.
@@ -310,45 +307,41 @@ pub struct ModuleData {
 }
 
 impl ModuleSource {
+    // precondition: item_id **must** point to module
+    fn new(file_id: FileId, item_id: SourceFileItemId) -> ModuleSource {
+        let source_item_id = SourceItemId { file_id, item_id };
+        ModuleSource(source_item_id)
+    }
+
+    pub(crate) fn new_file(db: &impl HirDatabase, file_id: FileId) -> ModuleSource {
+        let file_items = db.file_items(file_id);
+        let item_id = file_items.id_of_source_file();
+        ModuleSource::new(file_id, item_id)
+    }
+
     pub(crate) fn new_inline(
         db: &impl HirDatabase,
         file_id: FileId,
-        module: ast::Module,
+        m: ast::Module,
     ) -> ModuleSource {
-        assert!(!module.has_semi());
-        let items = db.file_items(file_id);
-        let item_id = items.id_of(module.syntax());
-        let id = SourceItemId { file_id, item_id };
-        ModuleSource::Module(id)
-    }
-
-    pub fn as_file(self) -> Option<FileId> {
-        match self {
-            ModuleSource::SourceFile(f) => Some(f),
-            ModuleSource::Module(..) => None,
-        }
+        assert!(!m.has_semi());
+        let file_items = db.file_items(file_id);
+        let item_id = file_items.id_of(m.syntax());
+        ModuleSource::new(file_id, item_id)
     }
 
     pub fn file_id(self) -> FileId {
-        match self {
-            ModuleSource::SourceFile(f) => f,
-            ModuleSource::Module(source_item_id) => source_item_id.file_id,
-        }
+        self.0.file_id
     }
 
     pub(crate) fn resolve(self, db: &impl HirDatabase) -> ModuleSourceNode {
-        match self {
-            ModuleSource::SourceFile(file_id) => {
-                let syntax = db.source_file(file_id);
-                ModuleSourceNode::SourceFile(syntax.ast().owned())
-            }
-            ModuleSource::Module(item_id) => {
-                let syntax = db.file_item(item_id);
-                let syntax = syntax.borrowed();
-                let module = ast::Module::cast(syntax).unwrap();
-                ModuleSourceNode::Module(module.owned())
-            }
+        let syntax_node = db.file_item(self.0);
+        let syntax_node = syntax_node.borrowed();
+        if let Some(file) = ast::SourceFile::cast(syntax_node) {
+            return ModuleSourceNode::SourceFile(file.owned());
         }
+        let module = ast::Module::cast(syntax_node).unwrap();
+        ModuleSourceNode::Module(module.owned())
     }
 }